28. c4b5 In two particular moments in this game, Carlsen plays extremely subtle moves that make it difficult for Black to defend. This is one of those educational moments. 28... c7c6  29. b5c4 The bishop simply goes back, but now the h2-b8 diagonal is open and the queen gains scope. 29... f7f6 Black is in trouble now. 30. e5e8 